The invention relates generally to the field of utility carts having a relatively horizontal load platform and foldable wheels. More particularly, the invention relates to the field of such carts where the wheels pivot above the load platform, such that the cart can be inserted into the bed of a vehicle with the load platform remaining horizontal.
Vehicles such as trucks, vans and station wagons are designed for transportation of large or bulky loads. Such loads are difficult to move or lift, so that loading them into or out of the vehicle is also difficult. Often the weight of the object or objects may require two individuals to load and remove. Carts have been manufactured which allow the user to place the cart, fully loaded with the goods to be transported, into the vehicle bed itself, even when the goods are very heavy. Once at the destination, the cart is removed from the vehicle, goods still loaded on it, and the goods taken to wherever desired. To accomplish this, the carts are structured so that the wheels are foldable, collapsible or pivotable. In practice, the end of the cart load platform is placed on vehicle bed, the wheels and any support members are folded, collapsed or pivoted out of the way and the main portion of the cart load platform is then shoved or rolled into the vehicle bed. Unloading the cart is accomplished by reversing the steps.
For example, Pratt in U.S. Pat. No. 3,082,016 teaches an auto cart having scissors type retractable wheels. The wheels are necessarily small in diameter, since the wheels fold toward the load platform of the cart and the frame actually rests on wheel axles for sliding the cart in and out of the vehicle. Hastings in U.S. Pat. No. 3,223,429 teaches a cart having small front wheels for use in the vehicle bed and large rear wheels for rolling the cart. The rear wheels pivot up to the cart load platform, but because of their size additional legs are required to maintain the load platform in horizontal position within the vehicle bed. Ferneau in U.S. Pat. No. 3,759,565 teaches a one-man cart having a set of scissors type wheels and a folding rear wheel support. A complicated adjustment mechanism allows the height of the cart to be altered. Eicher in U.S. Pat. No. 4,170,379 shows a trailer type hand cart having large wheels located on each side of the load platform. The wheels pivot to each side of the load platform for loading the cart into a vehicle. Bourgraf et al. in U.S. Pat. No. 4,369,985 teaches a cart having two sets of foldable wheels which collapse against the load bed when inserted into the vehicle platform.
The above devices suffer from various problems. Often the heavy load must be balanced and held up by the individual while the wheel structures are folded, collapsed or pivoted by pushing the frame against the vehicle. In most, the wheels remain below the surface of the load platform and support the load platform while in the vehicle bed, allowing the cart to roll and move within the vehicle. This can cause damage in the case of heavy loads. Some have small wheels, which are useless in circumstances with heavy loads on soft or non-level terrain. Most have complicated structures for folding the wheels and support members with excess pivots, latches, etc. which are subject to mechanical failure under heavy or repeated usage.
It is an object of the invention to provide a cart capable of supporting a heavy load and capable of movement over uneven or soft terrain which can be folded to allow the cart to be placed in the bed of a vehicle and removed while fully loaded with the cart load platform remaining horizontal.
It is a further object to provide such a cart where the mechanism for folding the wheels and support members is structurally simple, yet still capable of enduring heavy loads.
It is a further object to provide such a cart where the wheels and support members are pivoted above the level of the cart load platform so that the cart does not roll when placed within the vehicle bed.